I'm guessing she was thinking of sustained combat zones like Afghanistan...as for other locations
like Syria and Iraq, whenever our military is close to unsettled regions with opponents like ISIS, there will be isolated conflicts, but not anything that might be called an ongoing "War Zone"...dangerous, or sure...always...but KH was likely alluding to the scale of U.S. military involvement.
...from the attached article...
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"And as of today, there is not one member of the United States military who is in active duty in a combat zone, in any war zone around the world, the first time this century," Harris said.
That's not quite true.
The U.S. maintains nearly 1,000 troops on bases in Syria and another 2,500 in Iraq, according to the U.S. Department of Defense. In Syria, U.S. troops are stationed to help prevent a resurgence of the Islamic State group. They play a similar role in Iraq, where they also help disrupt Iran's influence and supply lines to various militias.
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I'm not sure that those deployments would get described as part of an historical "War" at this point in time.